What is GIS?

 
Examples:
Points: Parks
Lines: Streets
Polygons: Hydrographic
Raster: Airphoto
Raster: Digital Elevation Model
Combined Layers

See the News page for more examples.

 

GIS stands for Geographic Information Systems. Generally, it is a computerized sytem that manages spatial information. This spatial information is mainly comprised of raster data (continuous suface cover) and vector data (points, lines, and polygons) which serve as a model for actual physical features such as buildings, roads or counties. The spatial features may also be dynamically linked to an attribute database with a varied number of attributes.

Professions/Disciplines that use GIS:

There are many uses of GIS in many proffessional fields and disciplines. Uses range from proffesional industries such as utilities companies (power, water, communications, etc.), business marketing, health, forestry and environmental management, defense, cadastral/ tax assessment, urban planning, and oil or mineral exploration to name a few. Disciplines that find uses for GIS may include foresty and environmental studies, geography, architecture and urban planning, geology, archeaology, epidemiology and public health, social sciences/ demographics, history, and business/marketing. Find out more about how these industries/disciplines use GIS as described by the Environmental Systems Research Institute.

Types of GIS data:

Generally, there are 2 types of spatial data that can be used in a GIS: vector and raster. Vector data refers to data that contain features such as points, lines, or polygons. These features are often used as model to represent actual physical features. For example, points may represent physical features such as buildings, towns, hospitals, airports, gas stations, lighthouses, etc. Lines typical represent features such as roads, highways, streams, rivers, utility lines, and elevation contours. Polygons typically represent features such as political boundaries (countries, states, counties, towns, etc.), structures (building foot prints, industrial plants, football stadiums, etc.), habitat areas, parks, golf courses, and parcels.

Raster data refers to data that generally contain continuous features that completely cover an area. Instead of lines, points, and polygons, rater data is made up of pixels or cells. Common examples of raster data include air photos, satellite photos, land use/land cover data, and digital elevation models.

Data Formats:

There are a variety of digital formats for GIS vector and raster data just as there are a variety of GIS software available. See a table of the most common formats used in GIS.

GIS Jargon:

To access a more comprehensive dictionary of GIS terms, look at the AGI GIS dictionary.


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Last update: January 13, 2003 17:32
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